This invention relates to apparatus for measuring parameters of an RF signal. More particularly, it is concerned with apparatus for providing an instantaneous representation of the voltage, current, and phase of an RF signal.
Typically the values of the electrical parameters of voltage, current, and phase of an RF signal are determined by indirect measurements. In one technique directional couplers are inserted into the transmission line carrying the RF signal to measure the forward and reflected voltages present in the transmission line. The values of the electrical parameters are then determined by mathematical computations employing the measured data. In addition, when directional couplers are inserted in the transmission line and the coupling to the monitored RF signal is increased in order to increase measurement sensitivity, a significant disturbance is introduced into the system. Thus, the monitored RF signal is perturbed and the accuracy of the measurements is affected.